The invention relates generally to temperature measurement systems, and more particularly to multiwavelength pyrometry systems.
It is well known that the efficiency of gas turbine engines can be increased by raising the turbine operating temperature. As operating temperatures are increased, the thermal limits of certain engine components, such as the turbine blades or vanes, may be exceeded, resulting in reduced service life or even material failure. In addition, the increased thermal expansion and contraction of these components adversely affects clearances and their interfitting relationship with other components. Thus, it is desirable to monitor the temperature of hot gas path components during operation to assure that they do not exceed their maximum rated temperature for an appreciable period of time. Additionally, the desire to measure temperature extends to all heat engine applications where excessive working fluid temperatures can damage parts.
One approach to monitoring hot component temperatures is to measure the temperature of the gas leaving the engine and to use this as an indication of the part temperature. However, indirect temperature measurement techniques are relatively inaccurate, and approaches for measuring part temperatures directly have been proposed. One such technique, pyrometry, offers a number of advantages, as described below.
Pyrometers, also referred to as infrared thermometers, provide non-contact temperature measurements of an object and have been used to estimate temperatures of objects in a variety of industrial, scientific and commercial processes. One of the techniques in pyrometry that has been used is multi-wavelength pyrometry. In this technique, absolute temperature of an object is determined by sampling and combining radiation emitted by the object at multiple wavelengths.
However, for existing multi-wavelength pyrometer systems, incoming radiation from an object is split by a fixed beam splitter or a fixed semi-transparent mirror for transmission onto multiple detectors. Splitting the radiation results in less radiation being collected by each detector. As a consequence, longer acquisition times are necessary to obtain the desired accuracies. Generally, it has been seen that the data acquisition times for such systems are too slow to measure temperature profiles of rapidly moving parts and/or those undergoing rapid thermal change.
Therefore, there is a need for an improved multiwavelength pyrometry system to address the aforementioned issues.